[release-branch.go1.26] net/smtp: prevent test failures due to expired test certificate

The current localhostCert used for testing seems to have its expiry date
mistakenly set to Mar 18 19:27:54 2026 GMT.

To prevent test failures, use fixed time in tests. Also, regenerate the
certificate so we can fix the time to UNIX epoch (the current
certificate is only valid after Mar 18 2025).

Fixes #77532

Change-Id: I3136d29eaa0c8c4361f5627003f08a0059702f0d
Reviewed-on: https://go-review.googlesource.com/c/go/+/744260
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Roland Shoemaker <roland@golang.org>
Reviewed-by: Nicholas Husin <husin@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
(cherry picked from commit 215a070a049ce449480ca6948e7fafdeb7b16920)
Reviewed-on: https://go-review.googlesource.com/c/go/+/748061

1 files changed, 48 insertions, 43 deletions

diff --git a/src/net/smtp/smtp_test.go b/src/net/smtp/smtp_test.go
index 427ed0f7d9..b272b29dc5 100644
--- a/src/net/smtp/smtp_test.go
+++ b/src/net/smtp/smtp_test.go
@@ -1125,6 +1125,7 @@ func init() {
 	testRootCAs.AppendCertsFromPEM(localhostCert)
 	testHookStartTLS = func(config *tls.Config) {
 		config.RootCAs = testRootCAs
+		config.Time = func() time.Time { return time.Unix(0, 0) }
 	}
 }
 
@@ -1138,56 +1139,60 @@ func sendMail(hostPort string) error {
 //
 //	go run generate_cert.go --rsa-bits 2048 --host 127.0.0.1,::1,example.com \
 //		--ca --start-date "Jan 1 00:00:00 1970" --duration=1000000h
+//
+// The actual expiry time of this cert should not matter since we set
+// tls.Config.Time to be fixed in our tests.
 var localhostCert = []byte(`
 -----BEGIN CERTIFICATE-----
-MIIDFDCCAfygAwIBAgIRAPV4ktbcY/mn0oRRjnGAGJgwDQYJKoZIhvcNAQELBQAw
-EjEQMA4GA1UEChMHQWNtZSBDbzAeFw0yNTAzMTgxOTI3NTRaFw0yNjAzMTgxOTI3
-NTRaMBIxEDAOBgNVBAoTB0FjbWUgQ28wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAw
-ggEKAoIBAQDbsEfk1bK7ozwZlcQM8rBUikC4gwnnw0J1PUlGDGu1Y84dKtulbdWj
-yrh88D4fSdtmxFbXE7fhYUJTBmEHSUk9OLHh/Tr+nSC3SfH0I/9y6l9j9vVVYhYJ
-C07Z1mZZKVb+gmbbB7LEavGMNaFHjvRJAwBX2TMDbXJceZ9jU/iihILkZbrbG40r
-n1mctYVmcR3YqOzI/ynLje97FEvxtsg99OUjzzXyFMqfAl0J3Gc6tzvAER3N+ovK
-nudsnMB5Y+InQHHmPeizG4mFyeBYesXNwX6cmI30c8KFiAlKHcsxjJsuoBZ3bSwv
-vFdK2hnuCO05HEgCzAQKUlY6Q2F0xJblAgMBAAGjZTBjMA4GA1UdDwEB/wQEAwIF
-oDATBgNVHSUEDDAKBggrBgEFBQcDATAMBgNVHRMBAf8EAjAAMC4GA1UdEQQnMCWC
-C2V4YW1wbGUuY29thwR/AAABhxAAAAAAAAAAAAAAAAAAAAABMA0GCSqGSIb3DQEB
-CwUAA4IBAQBnfO4lYRXR9AdMidpgdITqMEKJik8MvCkpQ+EKQLq3CIGXPt5lkHLs
-ysbF9f3VxioKNYzkakJGVGyu51hqyhGqGQ4M7IpOBQkmY24IExWPVEk2wkIV+HTU
-+oQVZOIrHF+s9IIFOIh3SIPIsXNvx7rUc5sgF4P+eAnAcv3o1zL7YjGJZ8e27Ai2
-uF8iG/po/0Vd93OSB8Tj/Nvg99SSucy7nBYTreSdhUjZWRI0W1oYJX49/fhWljR9
-8+f2GqUfLc7iCjcV3wxlfBqEKCdpjXsiqtsb1KrAx7AEOj7XfDjJjyCL4bshLp9x
-PbV+kBFCN151iWYtfzhKEplrZFYNXlX2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 -----END CERTIFICATE-----`)
 
 // localhostKey is the private key for localhostCert.
 var localhostKey = []byte(testingKey(`
 -----BEGIN RSA TESTING KEY-----
-MIIEvgIBADANBgkqhkiG9w0BAQEFAASCBKgwggSkAgEAAoIBAQDbsEfk1bK7ozwZ
-lcQM8rBUikC4gwnnw0J1PUlGDGu1Y84dKtulbdWjyrh88D4fSdtmxFbXE7fhYUJT
-BmEHSUk9OLHh/Tr+nSC3SfH0I/9y6l9j9vVVYhYJC07Z1mZZKVb+gmbbB7LEavGM
-NaFHjvRJAwBX2TMDbXJceZ9jU/iihILkZbrbG40rn1mctYVmcR3YqOzI/ynLje97
-FEvxtsg99OUjzzXyFMqfAl0J3Gc6tzvAER3N+ovKnudsnMB5Y+InQHHmPeizG4mF
-yeBYesXNwX6cmI30c8KFiAlKHcsxjJsuoBZ3bSwvvFdK2hnuCO05HEgCzAQKUlY6
-Q2F0xJblAgMBAAECggEACzZIOQraBB8M3G5rEtEZBDuJGZGgggpSXDrsQC22mouV
-M6JiEuOT5Xfdagz10rF5h9lp6DCqsA8/bA7ViWJpYT1BQNwkdGWvC4Oz3EaxDRue
-kjLCqyCmKMCBvfbmAtNsC/G6T5/pNQKTQNlk2YrXd1l2nUUpyBlAHq2bX52jwSGD
-bFy5hyzSrzjeLpLUNZ56W/uXCvP0l6PAEvXRn/KG89XLZCtMBvVDMCfjIe77Q1U9
-/XzIrnb67RzQwiDelvX+biMkBrjeYw/Gvdo9hNCOfbOZ+SpnfDOLEfAha/XPmr3+
-5EeF4emeEhCODvfe7wy/4h1gHEG2N435S61DcV3gQQKBgQD92EJidwriPGDTUSM8
-nJrPQ5xwPMKz5hWpfI0zxIYZyqA37eRC5Q9WD3rDbrEZiLCInFh+Ci899iLzEpFZ
-dFQAUiRam+zFpDCQcGHr/uytRoTH/nxh2MrYPq8cA5ZGU6oMH+Yl4TynqJm2KN7e
-0ocE07QjyK/9nIvEtdibEiFEwQKBgQDdjcgoqHaM49YJ4yxGpjuRdc5a3iuKzZU6
-BON4GKqYQ9u/o8/NPaOSQ3vKhwzTjiEoOZImn+eX1cRP0ZskmQ+LyzsdVAHMDydz
-9I23dbIywtCXGhKOJRwt9O++8ataWIxi1frjj6BcI+TzGl8LM2lYIfUHzVzfswwE
-1EK8ikxnJQKBgBqPKvr0a54aJSNXBPHNjOEMuOyBXvnFpBSUpI17DXDbY4IWkOBy
-6PTfL8AM79i1FYtlmFivphu8ihGWqsCKTFOwRH96ev5+3FnweD5h8M98Zl4qgUcX
-kLmpbVboBSwcitkz6TejZl5AZLzLb+4uZtQZdmqcD9XgMDuHrz8iWXrBAoGBAMJO
-Z34pCRfVddFkGF+5yMJw5FLTSLLKTJb+1JRuZad21BIF0+i3p25OmxHrUXd0zmWd
-4CzZzt5eD3bFaOA3EOhUi/rTw2O44qwSjfuZUHiuXQw4RI+/wjAYAe+fud1ZjX3d
-FtVfEI/etxvyQ+rp4vj1hxWZqVtThzXxBrqePBW1AoGBAOTC19rFQXtVf9A+8c/w
-2ryAY2W9qNKe0xMivTAqau0Kdy2/2toJekR/5qOy3tOF7JasOgG+y3m3gLF47EFF
-v75eW4FkiCFvsyl/qv4CO1eKnHlvkRoDsnMb+dA5czst58rO6BK40QvPqwXaSxj1
-ee8ReNCDhC0Zidczajm63O1G
+MIIEvgIBADANBgkqhkiG9w0BAQEFAASCBKgwggSkAgEAAoIBAQDeSlcT6s/oeoRw
+t0AYO2cAmVKpeDG8+y762IPtQgkSZ21nStjEz7NB4twiswBBOh+dqzztZKnXCKNg
+9T8Njwu/0wesPAEi7piUGmXwZW2mXrGwX67SLohLUirPyMMaee5p/UW41JEILt50
+s464GxT65Lc+pSeC3wumszetpJZAk37KQg041EpOfHZcoCMHmJCIlhwIeX/iryk9
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+Mm4XJ0+cn7TqkzVc+7apwYk5kx+a1DCSomfbtd8XklocIhyP+3ZV2EjohHrat/YT
+xIYkjIwMfl8fQ/lVB0s/1UnyPy+7AatkCklNi8h2sZZuhkhG+zKJK8wXQd4WaMpf
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+UgGE703HtQKBgQCeIaLG6CqFMQejOrsBe0m1biUep9+TMvaDstmMH97eXZojD9H/
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+98q1SZ5NCZyERiZkH7qPZqgWHIUlCD3Wa7OJdyHOmfBjUH3Ord/WNGlWOQKBgQCv
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+7J1bJCBFkSWP+V39YY119Dkvg1GOifNHxDcHYf5/V+4iep0Bmd4hEjfmkq1hs6yx
+9a5907CVD3Pk31m06SqRoC0/cmFhVyR4hyM4PjWn8QKBgFz97Xe4VlllQ4v1lY3g
+1LXoF3oVBAcIiDOfnJuJKKUNJuQPfp7Z2/gisX/8RDPO+iBqKesUQxTKC2v6MOue
+YMR7L8AAn1wBFU5dioARmfBcVWBOpMZIHzHUqsnTqGzuIPTfnaZWxz13PbBxEiGS
++NeMNAdZn3grwXTdcD3VBVHs
 -----END RSA TESTING KEY-----`))
 
 func testingKey(s string) string { return strings.ReplaceAll(s, "TESTING KEY", "PRIVATE KEY") }